Downhole, hydraulically actuated, pumping apparatus generally include a hydraulically actuated engine which reciprocates a piston associated with a downhole pump so that production fluid enters the pump working chamber and is forced towards the surface of the earth along with spent power fluid from the engine. Hydraulically actuated, downhole pumps are very complex in design and are usually made for operation in deep, slim boreholes; and therefore, very little latitude is available to the pump manufacturer in selecting dimensions for the various mechanical components of the intricate engine and production pump mechanism.
In my previously issued U.S. Pat. No. 2,932,312, there is disclosed a valve system for pumps, which constitutes an improvement over the Coberly U.S. Pat. No. 2,081,222. Reference is made to these two previously issued patents for further background of this invention. In each of these two previously issued patents, there is disclosed a valve structure in the form of a circular hub which has an intake port formed therein by the formation of two intersecting constant diameter counterbores, with one of the counterbores being vertically disposed and located circumferentially spaced from the axial bore which receives the connecting rod therethrough, and with the remaining counterbore being normally arranged and radially disposed respective to the first counterbore. This configuration results in a considerable reduction in the structural integrity of the main valve body, because of the amount of material which must be removed from between the opposed faces of the valve body. Furthermore, the flow characteristics of the intake fluid flowing therethrough "washes out" interior portions of the valve assembly, especially since the production fluid often carries significant amounts of entrained, abrasive, foreign material during the pumping action.
The reduction in structural integrity resulting in the formation of the radial portion of the intake ports often leads to the formation of radial cracks which occur in the outer marginal edge of the valve structure in proximity of the intake ports, thereby rendering the pump inefficient in operation and sometimes inoperative. Furthermore, the undesirable flow characteristics imparted by the constant diameter radial counterbore contributes to maintenance problems. It is therefore desirable to provide a downhole, hydraulically actuated pump of a reciprocating type with improvements in the valve assembly associated therewith which exhibits increased structural integrity along with improved flow characteristics, so that the life of the entire system is significantly prolonged.